Interarch orthodontic coil springs are used for applying interarch tension during orthodontic treatment. The coil spring is typically attached at one end to a bracket bonded to a tooth on a patient's upper jaw and at the opposite end to a bracket bonded to a tooth on the lower jaw. Interarch tension may be applied to achieve a variety of objectives including stimulating growth, inducing incisor advancement, uprighting mandibular molars, and retracting the anterior segment of the maxillary arch.
One of the problems of some prior coil spring designs is that when attached to a bracket, the coil spring is caused to be bent over the buccal surface of the bracket. Such bending of the coil spring may reduce its effectiveness and shorten its useful life.
In addition, if the coil spring is positioned over the buccal surface of the bracket, the spring may more readily engage and irritate the patient's inner cheeks. Such irritation may cause some patients to remove or break these coil springs.
Moreover, if the coil spring is located over the buccal surface of the bracket, it may more readily engage or interfere with an arch wire retained in the bracket. Such interference or engagement between the arch wire and the coil spring may restrict movement of the arch wire and thereby lengthen the period of orthodontic treatment.
One object of the present invention is to provide a coil spring assembly that can be installed on orthodontic brackets without substantial bending of the coil spring. Another object of the invention is to provide a coil spring assembly that can be installed on orthodontic brackets while substantially limiting placement of the coil spring over the buccal surface of the brackets and limiting contact between the coil spring and arch wires retained in the brackets.